1. Technical Field
The present invention relates to cell module structures equipped in electric cars, hybrid electric cars, and the like, as a driving power supply. The cell modules in the invention include any type of charging element device, including cells such as nickel hydrogen batteries and lithium batteries; and energy storage devices such as double layered capacitors (ultra-capacitors).
2. Background Art
As a cell module in which plural cells are serially connected to each other, a conventional one is exemplified in which plural cylindrical or rectangular cells having a positive terminal and a negative terminal arranged at an end thereof are arranged in parallel, and the positive terminal and the negative terminal in adjoining cells are connected to each other via a bus bar so that the cells are connected to each other. The bus bar is generally mounted to the terminals by bolts or nuts in the assembly of the cell module.
FIG. 11 shows an example of a cell 200 and a bus bar 210 for a conventional cell module. In the example, a positive terminal 201 and a negative terminal 202 are arranged and project at an end of a cylindrical cell 200. The bus bar 210 consists of a positive bus bar 211 and a negative bus bar 212, which are insulated from each other and are penetrated by bolts 220 and 220, which are screwed to the positive terminal 201 and the negative terminal 202 so as to secure and serially connect them to each other.
In such a cell module, it is indispensable to monitor the conditions such as voltage and temperature of cells for safe and effective operations thereof. Therefore, a substrate equipped with a controlling circuit for the monitor is connected to the cells, and the power for the cells is transmitted to the substrate. An elastic conductive member such as a harness is usually used for connecting the cells and the substrate.
In the conventional cell module in which plural cells are serially connected to each other according to the connecting feature in FIG. 11, the task in which the bus bar is positioned with respect to the terminal and then the bolt is secured thereto must be repeated, so that the labor for connecting the terminals by a bus bar is substantial, and the number of parts is increased, and this results in increase of the weight. Furthermore, a large space for operating a securing tool is required for securing the bolts, and care to avoid short circuiting by the tool is necessary, and the connecting working is therefore further complicated.
In order to reduce the contact resistance in the connecting portion, the terminal and the bus bar must be rigidly secured. However, the load exerted on the connecting portion increases due to deformation thereof due to vibration and temperature changes, and the condition of the connection may therefore be deteriorated. In order to reduce the load exerted on the connecting portion, it has been proposed that the cells be supported by holding members. However, this proposal results in increase in the number of parts and complication of the structure.
In general, the area occupied by overall the cell and the cell module is readily large in the cell in which a positive terminal and a negative terminal are arranged at an end thereof, and this feature is disadvantageous for vehicles which are required to effectively utilize limited space.
It has been proposed to change the shapes of the positive terminal and the negative terminal to avoid misassembly in which the positive terminals are connected or negative terminals are connected. However, since the terminals are usually formed as protrusions, misassembly cannot be completely avoided. In addition, since the terminals are formed as protrusions, the terminals are often damaged by mishandling thereof. As a result, sufficient electrical contact cannot be obtained, or the terminals may short circuit in some cases.
In the connecting feature in which a control substrate is connected to cells by a harness, the current transmitted from the cells to the substrate is restricted by the resistance in the harness. Therefore, it is necessary to choose a harness having as a low resistance as possible. As a harness having low resistance, a harness with a short length, with a large cross section, or made from low resistance materials, may be mentioned. When the low resistance is achieved by the short length or the large cross section, arrangement of the harness may be difficult, and the position for locating the substrate may be restricted. In the cell modules in which plural cells are serially connected to each other, each cell must be connected to a harness, so that the task for connecting and the structure may be disadvantageously complicated.
Therefore, an object of the present invention is to provide cell module structures which can satisfy the following requirements.
(1) Cells can be easily connected and electrical resistance can be reduced.
(2) Number of parts can be reduced and the structure can be simple and light weight.
(3) Fine layout of cells can be performed and space is used effectively.
(4) Misassembly, damage, and short circuiting of cells can be avoided.
(5) Low resistance is achieved in connecting a controlling substrate and a cell, and complicated arrangement of a harness can be avoided.
The present invention has been made to achieve the above-mentioned objects. The invention provides a cell module structure comprising a bus bar plate and plural cylindrical cells; the bus bar plate including plural bus bars each having a positive bus bar terminal, a negative bus bar terminal, and a screw formed in one of the terminals, the bus bars being serially connected to each other with the positive bus bar terminal corresponding to the negative bus bar terminal; and a control substrate integrally provided to the bus bar and connected to the bus bars; the cell including a positive cell terminal and a negative cell terminal coaxially aligned at an end thereof, and a screw formed in the terminal having the same polarity as that of the bus bar terminal which is formed with the screw to which the above screw is screwed; wherein the screw of the cell is screwed to the screw of the bus bar, so that different terminals with no screw are brought into contact with each other, whereby the plural cells are serially connected.
According to the invention, the bus bars to which the cells are actually connected and the control substrate connected to the bus bars are integrally provided to the bus bar plate to which the cells are serially connected. The control substrate comprises, for example, a circuit for monitoring conditions such as voltage and temperature of the cells, and is driven by the power provided from the cells via the bus bar. When a cell module is formed, the screw formed in one of the terminals of the cell is fitted to the screw formed in one of the terminals of the bus bar in the bus bar plate, and the cell is rotated and secured. By this operation, the terminals with the screw are contacted to each other by the screw connection. By the screw action of the cell, the terminals with no screw are brought into contact with each other. By this connection, the plural cells are serially connected by each bus bar, and thus a cell module is formed.
According to the invention, the cell is screwed and secured to the bus bar, so that the positive terminal and the negative terminal of both are contacted with each other, and power is transmitted. Therefore, the contacting surface pressure between both can be sufficiently obtained, and the distance for electrical transmission can be extremely short, so that the electrical resistance can be greatly reduced. Furthermore, for the structure of screw securing, the rigidity of the connected condition of the cell and bus bar can be improved. As a result, the connected condition of the terminals can be rigidly maintained, so that the electrical resistance can be further reduced. In addition, the supporting member for the cell for reducing the load exerted on the connecting portion is not required, so that the number of parts is reduced and the structure can be simplified.
The positive terminal and the negative terminal of the cell can be serially connected to each other merely by screwing the cell to the bus bar, so that securing members such as bolts and nuts, and securing tools, are not needed. Therefore, the above operation for connecting can be performed very easily, and the space for the operation can be reduced. In addition, the space occupied by overall the cell and the cell module can be reduced, so that limited space can be utilized effectively. Moreover, the number of parts can be reduced and the structure can be simple and light weight. The connecting operation can be more easily performed since the operator need not confirm the polarity of the terminal of the cell in connecting the cell to the bus bar plate, and misassembly of the same polarity and short circuiting due to this can be avoided.
In the invention, the control substrate is integrally provided with the bus bar plate in the condition in which the control substrate is connected to the bus bar, and the power of the cells is directly provided to the control substrate via the bus bar. Therefore, the electrical resistance of the power supply line from cells to the control substrate can be easily reduced. Moreover, it is not necessary for a substrate and a harness to be arranged for each cell around a bus bar plate as in the conventional art, so that the connecting operation and the structure are not complicated.
The following are preferred features of the invention.
The bus bar may comprise a plate-shaped bus bar body, which is integrally formed with the positive bus bar terminal and the negative bus bar terminal. The bus bar integrally formed can be stronger than a divided structure, the number of parts can be reduced, and the connecting operation can be simple.
In the adjoined pair of the bus bars in the bus bar plate, the positive bus bar terminal of one of the bus bars and the negative bus bar terminal of another bus bar may be coaxially aligned holding a cylindrical insulating member therebetween, the insulating member may include a coaxially aligning member for contacting the bus bar, thereby maintaining the coaxial alignment with the bus bar. The bus bars arranged in the bus bar plate are serially connected each other corresponding the positive bus bar terminal and the negative bus bar terminal of the adjoined bus bars, and these terminals are connected to the terminals of the cells. Since the positive cell terminal and the negative cell terminal of the cell are coaxially aligned, the terminals of the bus bar need to be coaxially aligned. The coaxial alignment is maintained by a coaxially aligning member provided to the insulating member. As a result, the terminals of the cell and the terminals of the bus bar can be reliably connected.
The bus bar plate may comprise a first plate disposed at a side where the cell is mounted, and a second plate which holds the bus bar associating with the first plate, the first plate may comprise a fitting portion which supports a reaction from the bus bar plate due to a screwing torque generated when the screw of the cell is screwed to the screw of the bus bar, and may engage with the bus bar so as to prevent extraction of the bus bar. In this feature, the torque by the screwed cell is reliably generated by the fitting portion formed in the second plate, and the bus bar is not extracted.
The three cells may be arranged to form a regular triangle, which is a unit of cell arrangement. In this feature, fine layout of the cells can be obtained, and the overall cell module can be compact and the space can be effectively utilized.
The bus bar may comprise a measuring device for measuring a temperature of the cell. By measuring the temperature of the cells by the measuring device, the operating condition of the cells can be monitored, which will ensure safe operation thereof.
The bus bar plate may comprise plural ribs extending between the cells, a columnar portion may be provided at an intersection of the ribs, and the columnar portion may be provided with a measuring device for measuring temperatures of the cells around the columnar portion. The rib arranged between cells improves strength of the bus bar plate, and short circuiting between the adjoined cells due to harmful materials such as water droplets adhered to the bus bar plate can be avoided by the rib. Furthermore, in forming the bus bar plate by a resin, flowability of resin is obtained and formability thereof can be improved due to the columnar portion at the intersection of the ribs. Moreover, the temperatures of the cells around the columnar portion can be measured by installing the measuring device for temperatures of the cells in the columnar portion.